Flow Past a Backward-Facing Step: Comparison of PANS, DES and URANS Results with Experiments

Abstract

Flow past a backward-facing step is computed using three different turbulence modeling approaches; Detached Eddy Simulation (DES), Unsteady Reynolds Averaged Navier-Stokes (URANS), and the newly developed Partially Averaged Navier-Stokes (PANS) [ 1 Girimaji, S. S. 2006. Partially-averaged Navier-Stokes model for turbulence: A Reynolds-averaged Navier-Stokes to direct numerical simulation bridging method. Journal of Applied Mechanics, 73: 413–421. [Crossref], [Web of Science ®] [Google Scholar] , 2 Girimaji, S. S. , Jeong, E. and Srinivasan, R. 2006. Partially averaged Navier-Stokes method for turbulence: Fixed point analysis and comparison with unsteady partially averaged Navier stokes. Journal of Applied Mechanics, 73: 422–429. [Crossref], [Web of Science ®] [Google Scholar] ] method. PANS is a family of closure models parameterized by different ratios of resolved-to-modeled kinetic energy and dissipation. The corresponding resolution control parameters are f _k (the ratio of unresolved to total kinetic energy) and f _ϵ (the ratio of unresolved-to-total dissipation). The main objectives of this study are: (i) to investigate the merits of PANS relative to the other two methods by comparing against existing experimental data; and (ii) to examine the effect of the PANS parameter f _ϵ on the computed flow field. In addition, we study the sensitivity of PANS results to grid-size and the level of unsteadiness in the inflow. Overall, the results clearly demonstrate the suitability of PANS for computing unsteady turbulent flows at a reasonable computational expense.